The present invention relates to a method for manufacturing a magnetic recording medium mounted in magnetic storage devices used in data storage devices of data processing devices such as computers. More specifically, the present invention relates to a method for forming a lubricating film disposed on a protective film of the magnetic recording medium.
Generally, magnetic storage devices (hard disk drives) (hereinafter also referred to as device) include a magnetic recording medium (magnetic disk medium) (hereinafter also referred to as medium) rotatable at high speeds, and a magnetic head facing the medium. Data are written to the medium and data recorded on the medium are read by having the magnetic head fly slightly above the medium rotating at high speeds due to the air currents generated by the rotation of the medium. The data recording density of the medium is greater when the distance between the magnetic layer of the medium and the magnetic head (the magnetic head flight) is small. Devices generally use the CSS (Contact Start Stop) system. When the device is inactive, the magnetic head is resting on the static medium surface. When the device is starting up or is stopping, the magnetic head temporarily makes sliding contact with the medium that is spinning up or spinning down. To allow the sliding contact to be smooth when this happens, a lubricant film is generally disposed on the medium surface.
Conventionally, the lubricant film for this type of medium is formed using methods such as: dipping, where a non-magnetic substrate formed with everything up to a protective film (hereinafter referred to as substrate with protective film) is immersed in a container of lubricant solution and then pulled up; spin-coating, where a lubricant solution is dripped to the surface of the protective film on a rotating substrate with protective film; and fluid drainage, where a substrate with protective film is immersed in a lubricant solution, and then the lubricant solution is allowed to flow out from the bottom of the container with the help of gravity.
The lubricant film of the medium is important for maintaining the reliability of the magnetic storage device since it provides smoothness during the temporary sliding contact between the surface of the medium and the magnetic head when the device is being started or stopped. In particular, there has been a growing demand for increased storage capacity in devices, and there is a need to keep the magnetic head flight small when the device is operating. Thus, film thickness of the lubricant film and variations in the film thickness must be kept within the order of angstroms. As a result, surrounding air currents during formation of the lubricant film must be eliminated and vibration from support mechanisms, drive mechanisms and the like for the substrate with protective film must be eliminated. Also, contamination of the lubricant solution from organic gas, inorganic gas, and particles present in the film-forming atmosphere must be prevented. Furthermore, transpiration of solvent from the lubricant solution can result in changes in the concentration of the lubricant solution, resulting in changes in the thickness of the lubricant film being formed. For this reason, transpiration of the solvent must be prevented. Furthermore, when fluorine-based solvents are used as the solvent in the lubricant solution, environmental considerations require that transpiration of the solvent vapor to the atmosphere must be reduced as much as possible.